Communication terminal, server device, movement guidance system, and computer program

ABSTRACT

There are provided a communication terminal, a server device, a movement guidance system, and a computer program that can provide movement guidance based on a new version of map information soon after starting up the communication terminal. Specifically, a communication terminal 5 is configured to identify, after its startup, update target areas which are areas whose terminal-side map information 48 included in the communication terminal 5 is an older version of map information than device-side map information 25 included in a server device 3; request the server device 3 for movement guidance information 26 targeted for at least update target areas around a current location, the movement guidance information 26 being used to provide movement guidance for a mobile unit; and provide movement guidance for the mobile unit using movement guidance information 26 transmitted from the server device 3 in response to the request.

TECHNICAL FIELD

Related technical fields include fields pertaining to a communication terminal, a server device, a movement guidance system, and a computer program that provide movement guidance for a mobile unit.

BACKGROUND

In recent years, a navigation device that provides vehicle travel guidance so that a driver can easily reach a desired destination has been often mounted on a vehicle. Here, the navigation device is a device capable of detecting a current location of the vehicle by a GPS receiver, etc., obtaining map information for the current location through a recording medium such as a DVD-ROM or an HDD or a network, and displaying the map information on a liquid crystal monitor. In addition, the above-described navigation device has a route search function that searches for, when a desired destination is set, an optimal route from a point of departure (e.g., a current location of the vehicle) to the set destination, and further has a travel guidance function that provides travel guidance along the searched route (guidance route). In addition, in recent years, there have been mobile phones, personal digital assistants (PDAs), smartphones, personal computers, etc., that have the same functions as the above-described navigation device (hereinafter, referred to as communication terminals including a navigation device).

Here, new roads (newly constructed roads) are constructed all over Japan every year. In addition, along with this, existing roads disappear, intersections are added, or the shapes of existing roads or intersections are changed. At that time, there is a problem that information about newly constructed roads, etc., that are newly constructed after creating map information included in a communication terminal is not registered in the map information. Namely, in the communication terminal having map information that does not include newly constructed roads, etc., since the newly constructed roads, etc., do not serve as targets for a route search or guidance, appropriate travel guidance may not be provided, e.g., a roundabout guidance route that does not pass through a newly constructed road, etc., is searched for, or guidance on roads or intersections that actually exist is not provided on a map image.

In view of this, in recent years, there has been proposed a configuration in which a server device having the latest map information performs a route search instead of a communication terminal side, and a guidance route is obtained from the server device (hereinafter, referred to as a center route search). However, when a center route search has been performed, while a route can be searched for based on the latest map information, there has been a problem that the communication terminal side having an old version of map information cannot appropriately provide travel guidance along a guidance route. For example, when a target guidance intersection at which a left or right turn is made in a guidance route is a newly constructed intersection, left or right turn guidance at the guidance intersection is not provided. In addition, in the case of an intersection whose structure has been changed, guidance on the wrong direction is provided based on old map information.

As means for avoiding the above-described problems upon performing a center route search, for example, JP 2003-77095 A proposes a technique in which when a server device receives a route search request from a navigation device, while the server device searches for a route, the server device transmits the mesh codes and version information of meshes through which the searched route passes, together with the searched route, to the navigation device, and the navigation device determines, based on the mesh codes and version information transmitted from the server device, whether the versions of corresponding pieces of mesh data (map information) are older than those of pieces of mesh data stored in the server device, and requests the server device for the latest versions of pieces of mesh data targeted for meshes having been determined to be old.

SUMMARY

Here, in the technique of the above-described JP 2003-77095 A, first, the server device performs a route search and after determining a guidance route, it is determined whether the latest version of mesh data needs to be obtained from the server device. Then, if it is determined that the latest version of mesh data needs to be obtained, the navigation device thereafter requests the server device for mesh data at a later time point. Therefore, it requires a very long time to obtain required mesh data after setting a guidance route, and thus, problems occur, e.g., guidance based on the guidance route cannot be provided during such a period or erroneous guidance is provided. In addition, there has been a possibility that the navigation device provides travel guidance based on an old version of map information during a period from when the navigation device starts up to when mesh data is obtained.

Furthermore, in the above-described JP 2003-77095 A, there has been another problem that since mesh data (map information) received by the navigation device from the server device is large-sized information that includes facility data, data used for a route search, etc., in addition to guidance information for providing movement guidance, the amount of communication between the navigation device and the server device increases and the time required for the communication also increases.

Exemplary embodiments of the broad inventive principles described herein solve the above-described conventional problems, and provide a communication terminal, a server device, a movement guidance system, and a computer program that can provide movement guidance based on a new version of map information soon after starting up the communication terminal, and that can appropriately provide movement guidance based on a guidance route even after the communication terminal obtains the guidance route from the server device, and that can further reduce the amount of communication between the communication terminal and the server device.

Exemplary embodiments provide a communication terminal that is connected to a server device in a two-way communicable manner and that transmits a route search request for a destination to the server device and obtains a route searched for and delivered by the server device in response to the route search request. Specifically, the communication terminal requests the server device for guidance information after starting up the communication terminal, the guidance information being used to provide movement guidance for a mobile unit and being targeted for at least an update target area around a current location among update target areas, the update target areas being areas whose terminal-side map information included in the communication terminal is an older version of map information than device-side map information included in the server device. The communication terminal receives the guidance information transmitted from the server device in response to the request for the guidance information and provides movement guidance for the mobile unit using a guidance route set on the communication terminal and the received guidance information.

Note that the “mobile unit” also includes a pedestrian and a two-wheeled vehicle in addition to a vehicle.

Note also that the “version of map information” includes any of the creation time of the map information, an update time when the last update to the map information is made, and a time when map update information (update program) used when the last update is made is created.

Exemplary embodiments provide a computer program according to that transmits a route search request for a destination to a server device connected in a two-way communicable manner, and obtains a route searched for and delivered by the server device in response to the route search request. Specifically, the computer program causes a communication terminal to perform functions including (i) requesting the server device for guidance information after starting up the communication terminal, the guidance information being used to provide movement guidance for a mobile unit and being targeted for at least an update target area around a current location among update target areas, the update target areas being areas whose terminal-side map information included in the communication terminal is an older version of map information than device-side map information included in the server device; (ii) receiving the guidance information transmitted from the server device in response to the request for the guidance information; and (iii) providing movement guidance for the mobile unit using a guidance route set on the communication terminal and the received guidance information.

Exemplary embodiments provide a server device that is connected to a communication terminal in a two-way communicable manner and that receives a route search request for a destination from the communication terminal and delivers a route searched for in response to the received route search request to the communication terminal. Specifically, the server device receives a request for guidance information for providing movement guidance for a mobile unit from the communication terminal having started up and transmits the guidance information to the communication terminal in response to the request for the guidance information, the guidance information being targeted for at least an update target area around a current location among update target areas, the update target areas being areas whose terminal-side map information included in the communication terminal is an older version of map information than device-side map information included in the server device.

In addition, a movement guidance system according to the present invention includes the above-described server device and terminal device.

According to the communication terminal, the server device, the movement guidance system, and the computer program that have the above-described configurations, since guidance information for providing movement guidance for a mobile unit is obtained after starting up the communication terminal, it becomes possible to provide movement guidance based on a new version of map information soon after starting up the communication terminal. In addition, upon performing a center route search, by obtaining in advance guidance information for providing movement guidance for the mobile unit, the occurrence of an event in which after the communication terminal obtains a guidance route from the server device, movement guidance based on the guidance route is not provided or erroneous guidance is provided can be prevented as much as possible. As a result, even if map information included in the communication terminal is an older version of map information compared to map information included in the server device, it becomes possible to appropriately provide movement guidance for the mobile unit based on a guidance route searched for by the server device. Furthermore, instead of map information (including facility data, data used for a route search, etc., in addition to guidance information for providing movement guidance), the guidance information which is part of the map information is selectively obtained in advance from the server device, and thus, it becomes possible to reduce the amount of information delivered compared to the case of obtaining map information.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic configuration diagram showing a movement guidance system according to the present embodiment.

FIG. 2 is a block diagram showing a configuration of the movement guidance system according to the present embodiment.

FIG. 3 is a block diagram schematically showing a control system of a communication terminal according to the present embodiment.

FIG. 4 is a diagram showing an example of an update area table.

FIG. 5 is a diagram showing an example of movement guidance information stored in a cache.

FIG. 6 is a flowchart of a movement guidance processing program according to the present embodiment.

FIG. 7 is a flowchart of the movement guidance processing program according to the present embodiment.

FIG. 8 is a diagram showing an example of table update information.

FIG. 9 is a diagram showing an exemplary update to the update area table.

FIG. 10 is a diagram showing target areas whose movement guidance information is requested.

FIG. 11 is a diagram showing target areas whose movement guidance information is requested.

FIG. 12 is a flowchart of a sub-processing program for a cache management process.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

An embodiment in which a movement guidance device and a computer program are embodied will be described in detail below with reference to the drawings. First, a schematic configuration of a movement guidance system 1 according to the present embodiment will be described using FIGS. 1 and 2 . FIG. 1 is a schematic configuration diagram showing the movement guidance system 1 according to the present embodiment. FIG. 2 is a block diagram showing a configuration of the movement guidance system 1 according to the present embodiment.

As shown in FIG. 1 , the movement guidance system 1 according to the present embodiment basically includes a server device 3 provided in a map information center 2; and communication terminals 5 carried by users 4. In addition, the server device 3 and the communication terminals 5 are configured to be able to perform transmission and reception of electronic data with each other through a communication network 6. Note that the communication terminals 5 include, for example, mobile phones, smartphones, tablet terminals, personal computers, and navigation devices. In addition, the users 4 may be in a state of getting in vehicles or may be in a state of not getting in vehicles.

Here, the server device 3 performs a route search in response to a request from a communication terminal 5. Specifically, when the communication terminal 5 has set a destination or performs a re-search for a route (rerouting), the communication terminal 5 transmits information required for a route search such as a point of departure and a destination, together with a route search request, to the server device 3 (note, however, that in the case of a re-search, information about a destination does not necessarily need to be transmitted). Then, the server device 3 having received the route search request performs a route search using map information included in the server device 3, and identifies a recommended route from the point of departure to the destination. Thereafter, the identified recommended route is transmitted to the communication terminal 5 which is the request source. Then, the communication terminal 5 sets the received recommended route as a guidance route, and provides movement guidance along the guidance route. By this, even if map information included in the communication terminal 5 at the time of a route search is an old version of map information, an appropriate guidance route can be set based on the latest version of map information included in the server device 3.

In addition to the delivery of the above-described searched route, the server device 3 also delivers movement guidance information for providing movement guidance for a user on the communication terminal 5, in response to a request from the communication terminal 5. Note that the movement guidance information is information created based on the latest version of map information and used to identify a current location, provide simple travel guidance along a guidance route, and display an image on the communication terminal 5 according to the latest version of map information as will be described later. Then, by the communication terminal 5 using the movement guidance information delivered from the server device 3, even if map information included in the communication terminal 5 is an old version of map information, the communication terminal 5 can provide movement guidance along a guidance route having been searched for by the server device 3 based on the latest version of map information.

Meanwhile, for the communication terminal 5, an information terminal having navigation functions and carried by a user 4 is used. The communication terminal 5 corresponds, for example, to a mobile phone, a smartphone, a tablet terminal, a personal computer, or a navigation device.

Here, the navigation functions correspond to the functions of searching for a route appropriate to conditions specified by the user, displaying a map image of an area around a current location of the user 4, displaying the current location of the user 4 in the displayed map image, and providing movement guidance along a set guidance route. Note that the communication terminal 5 does not need to have all of the above-described navigation functions, and the invention of the present application can be formed as long as the communication terminal 5 has at least the function of searching for a route and the function of providing movement guidance along a set guidance route.

In addition, the communication network 6 includes multiple base stations disposed all over the country and telecommunications companies that manage and control the base stations, and is formed by connecting the base stations to the telecommunications companies by wire (optical fiber, ISDN, etc.) or wirelessly. Here, each base station includes a transceiver and an antenna that perform communication with communication terminals 5. While the base station performs radio communication with a telecommunications company, the base station serves as an end of the communication network 6 and plays a role in relaying communication of communication terminals 5 present in an area (cell) in which radio waves from the base station reach, with the server device 3.

Next, a configuration of the server device 3 in the movement guidance system 1 will be described in more detail using FIG. 2 . The server device 3 includes, as shown in FIG. 2 , a server control ECU 11; a device-side map DB 12 connected to the server control ECU 11 and serving as information storage medium; and a server-side communication device 13. (As used herein the term “storage medium” incudes all tangible media that can store computer-readable data, but does not encompass transitory signals.)

The server control ECU 11 (electronic control unit) is an electronic control unit that performs overall control of the server device 3, and includes a CPU 21 serving as a computing device and a control device; and internal storage devices such as a RAM 22 used as a working memory when the CPU 21 performs various types of arithmetic processing, a ROM 23 having recorded therein a movement guidance processing program which will be described later (see FIGS. 6 and 7 ), etc., in addition to a program for control, and a flash memory 24 that stores a program read from the ROM 23. Note that the server control ECU 11 includes various types of means serving as processing algorithms with an ECU of a communication terminal 5 which will be described later. For example, guidance information request receiving means receives a request for movement guidance information for providing movement guidance for a mobile unit (e.g., a user him/herself or a vehicle) from a communication terminal 5. Guidance information transmitting means transmits movement guidance information for target areas to the communication terminal 5, in response to the request for movement guidance information.

In addition, the device-side map DB 12 is storage means for storing device-side map information 25 such that the device-side map information 25 is divided on a per area basis (e.g., on a per level-10 mesh basis, the mesh being of 20 km square). The device-side map information 25 is the latest version of map information registered based on input data from an external source and input operations. Here, the version is creation time information for identifying a time when map information is created, a time when the last update is made, or a time when map update information (update program) used when the last update is made is created. By referring to the version, the time when map information is created, etc., can be identified.

Here, the device-side map information 25 basically has the same configuration as map information stored in the communication terminals 5, and includes a road network and various types of information required for a route search, route guidance, and map display. The device-side map information 25 includes, for example, link data about roads (links), node data about node points, intersection data about each intersection, location data about locations such as facilities, map display data for displaying a map, search data for searching for a route, and retrieval data for retrieving a location.

For the search data, various types of data are recorded that are used in a route search process for searching for a route from a point of departure (e.g., a current vehicle location) to a set destination as will be described later. For example, cost calculation data is stored that is used to calculate search costs such as a cost which is a numerical representation of the level of appropriateness of an intersection for a route (hereinafter, referred to as an intersection cost) and a cost which is a numerical representation of the level of appropriateness of a link forming a road for the route (hereinafter, referred to as a link cost).

In addition, the device-side map DB 12 also stores, separately from the device-side map information 25, movement guidance information 26 such that the movement guidance information 26 is divided on a per area basis (e.g., on a per level-13 mesh basis, the mesh being of 2.5 km square). The movement guidance information 26 is information for identifying a current location and providing simple travel guidance along a guidance route on the communication terminals 5 according to the latest version of map information.

Here, the movement guidance information 26 includes matching data required to perform map matching for a current user location; guidance data required for guidance for allowing a user to move along a guidance route, such as left or right turn guidance at guidance intersections; and display data for displaying a map image and a guidance screen. Note that the matching data includes, for example, data for identifying road shapes. In addition, the guidance data includes, for example, data for identifying the shapes of intersections and a connection relationship between intersections and roads. In addition, the display data includes data for displaying, on a display of a communication terminal 5, a map image including a road network and a guidance screen for providing movement guidance.

When the server control ECU 11 receives a route search request from a communication terminal 5 as will be described later, the server control ECU 11 searches for a route from a point of departure to a destination, using the device-side map information 25. Then, the searched route is delivered to the requested communication terminal 5. In addition, the server control ECU 11 also delivers movement guidance information 26 to the communication terminal 5 as necessary. Specifically, the server control ECU 11 is configured to deliver movement guidance information 26 for target areas to the communication terminal 5, the target areas being areas in which the communication terminal 5 is likely to move in the future (e.g., areas around a current location of the communication terminal 5 and areas around a guidance route set on the communication terminal 5), and whose map information included in the communication terminal 5 is an older version than device-side map information 25, i.e., areas that require movement guidance information 26 for the future movement guidance on the communication terminal 5.

Meanwhile, the server-side communication device 13 is a communication device for performing communication with the communication terminals 5 through the communication network 6. In addition, the server-side communication device 13 can also receive traffic information including various pieces of information such as congestion information, regulation information, and traffic accident information which are transmitted from an Internet network or traffic information centers, e.g., a VICS (registered trademark: Vehicle Information and Communication System) center and a probe center, in addition to the communication terminals 5.

Next, a schematic configuration of a communication terminal 5 will be described using FIG. 3 . Note that the following description is made of an example case in which a navigation device installed in a vehicle is used as the communication terminal 5, and travel guidance for particularly the vehicle serving as a mobile unit is provided. Note, however, that instead of a navigation device, a mobile phone, a tablet terminal, a personal computer, etc., may be used. In addition, when a mobile phone or a tablet terminal is used, it is also possible to provide movement guidance for a mobile unit other than a vehicle (e.g., a pedestrian or a bicycle). FIG. 3 is a block diagram schematically showing a control system of a navigation device which is a communication terminal 5 according to the present embodiment.

As shown in FIG. 3 , the communication terminal 5 according to the present embodiment includes a current location detecting part 31 that detects a current location of a vehicle (mobile unit) having mounted thereon a navigation device which is the communication terminal 5; a data recording part 32 having various types of data recorded therein; a navigation ECU 33 that performs various types of arithmetic processing based on inputted information; an operating part 34 that accepts operations from a user; a liquid crystal display 35 that displays a map and a guidance route to a destination to the user; a speaker 36 that outputs audio guidance regarding route guidance; a DVD drive 37 that reads a DVD which is a storage medium; and a communication module 38 that performs communication with the server device 3, a VICS center, etc.

The components included in the communication terminal 5 will be described in turn below.

The current location detecting part 31 includes a GPS 41, a vehicle speed sensor 42, a steering sensor 43, a gyro sensor 44, etc., and can detect a current vehicle location, orientation, vehicle travel speed, current time, etc. Here, particularly, the vehicle speed sensor 42 is a sensor for detecting the movement distance and vehicle speed of the vehicle, and generates pulses according to the rotation of drive wheels of the vehicle and outputs a pulse signal to the navigation ECU 33. Then, the navigation ECU 33 counts the generated pulses and thereby calculates the rotational speed of the drive wheels and movement distance. Note that the communication terminal 5 does not need to include all of the above-described four types of sensors, and the communication terminal 5 may be configured to include only one or a plurality of types of sensors among those sensors.

In addition, the data recording part 32 includes a hard disk (not shown) serving as an external storage device and a recording medium; and a recording head (not shown) which is a driver for reading a terminal-side map DB 45, a version management DB 46, a cache 47, a predetermined program, and the like, which are recorded on the hard disk, and writing predetermined data to the hard disk. Note that the data recording part 32 may be composed of a nonvolatile memory, a memory card, or an optical disc such as a CD or a DVD, instead of a hard disk.

Here, the terminal-side map DB 45 is storage means for storing terminal-side map information 48 used for a route search and travel guidance on the communication terminal 5.

Here, the terminal-side map information 48 stored in the terminal-side map DB 45 includes, as with the above-described device-side map information 25, a road network and various types of information required for a route search, route guidance, and map display. The terminal-side map information 48 includes, for example, link data about roads (links), node data about node points, intersection data about each intersection, location data about locations such as facilities, map display data for displaying a map, search data for searching for a route, and retrieval data for retrieving a location.

In addition, the terminal-side map information 48 stored in the terminal-side map DB 45 is updated to a new version of map information on a section-by-section basis (e.g., on a mesh-by-mesh basis) by writing new data over data for a corresponding portion based on map update information delivered from a map delivery server which is not shown or map update information obtained from a recording medium. In addition, it is also possible to make an update to the entire map information instead of on a section-by-section basis. In addition, the terminal-side map DB 45 also stores movement guidance information 26 for identifying a current location, providing travel guidance along a guidance route, and displaying an image on the communication terminals 5 according to map information, such that the movement guidance information 26 is divided on a per area basis (e.g., on a per level-13 mesh basis, the mesh being of 2.5 km square).

In addition, the version management DB 46 is storage means for recording information that identifies the versions of pieces of terminal-side map information 48 currently stored in the terminal-side map DB 45 (e.g., version numbers, the last updated dates and times, or the creation dates and times of pieces of map update information (update programs) having made the last update), on a section-by-section basis (e.g., on a mesh-by-mesh basis) of map information. Note that with an update of terminal-side map information 48 to a new version of map information, corresponding content of the version management DB 46 is updated.

In addition, the version management DB 46 stores an update area table (area identification information) 49 as information that identifies an area (hereinafter, referred to as an update target area) whose terminal-side map information 48 included in the communication terminal 5 is an older version of map information than device-side map information 25 included in the server device 3. Here, the update area table 49 is a table in which flags that identify a section corresponding to an update target area and a section not corresponding to an update target area are assigned on a section-by-section basis (e.g., on a mesh-by-mesh basis) of map information. FIG. 4 shows an example of the update area table 49.

FIG. 4 shows a state in which a road has been newly constructed and of the meshes forming the device-side map information 25 included in the server device 3, a total of six meshes which are corresponding areas have been updated from the previous version “50” to the new version “60”. In this situation, the terminal-side map information 48 included in the communication terminal 5 is before being updated at the present time, and pieces of terminal-side map information 48 for the meshes whose device-side map information 25 has been updated to the version “60” still have the version “50”. Namely, there are update target areas whose terminal-side map information 48 included in the communication terminal 5 is an older version of map information than device-side map information 25 included in the server device 3. As shown in FIG. 4 , in the update area table 49, flags that identify a section corresponding to an update target area and a section not corresponding to an update target area are assigned on a mesh-by-mesh basis. Specifically, “0” is assigned to a mesh corresponding to an update target area, and “1” is assigned to a mesh not corresponding to an update target area. Note that although the example shown in FIG. 4 shows the update area table 49 targeted for 5×5 meshes for simplification of description, the actual update area table 49 is a table in which flags are assigned to each of meshes forming all areas of the country (when a mesh includes a plurality of levels, flags are assigned on an area-by-area basis and on a level-by-level basis).

As a result, by referring to the update area table 49, the navigation ECU 33 can easily identify update target areas (i.e., areas whose terminal-side map information 48 included in the communication terminal 5 is an older version of map information than device-side map information 25 included in the server device 3). Note that the update area table 49 is updated as appropriate based on update information transmitted from the server device 3, as will be described later. For example, when device-side map information 25 or terminal-side map information 48 is updated to a new version of map information, the update area table 49 is also updated accordingly. Note that for a standard for area sections for the update area table 49, a common standard between the server device 3 and the communication terminal 5 is used.

Meanwhile, the cache 47 is storage means for temporarily saving movement guidance information 26 which is delivered from the server device 3. In the movement guidance system 1 according to the present embodiment, as described previously, movement guidance information 26 targeted for areas is delivered from the server device 3 and stored in the cache 47, the areas being areas in which the vehicle is likely to travel in the future (e.g., areas around a current vehicle location and areas around a guidance route set on the communication terminal 5) and whose terminal-side map information 48 included in the communication terminal 5 is an older version than device-side map information 25, i.e., areas that require movement guidance information 26 for the future vehicle movement guidance. Here, the movement guidance information 26 is, as described previously, information for identifying a current location, providing simple travel guidance along a guidance route, and displaying an image on the communication terminal 5 according to the latest map information.

Then, the navigation ECU 33 performs identification of a current vehicle location, travel guidance along a guidance route, display of an image, etc., for the areas whose terminal-side map information 48 included in the communication terminal 5 is an older version than device-side map information 25, using a new version of the movement guidance information 26 stored in the cache 47, instead of an old version of map information and movement guidance information stored in the terminal-side map DB 45.

In addition, the movement guidance information 26 stored in the cache 47 is set with remaining priorities on a section-by-section basis (e.g., on a mesh-by-mesh basis) of map information. When the storage area of the cache 47 is lacking, of the pieces of movement guidance information 26 stored in the cache 47, pieces of movement guidance information 26 for area sections with a low remaining priority are deleted on a priority basis. Note that as will be described later, a higher remaining priority is set for movement guidance information 26 for area sections that require movement guidance information for the future vehicle movement guidance, more specifically, area sections located around a current vehicle location, and movement guidance information 26 for area sections located around a guidance route set on the communication terminal 5 than that for movement guidance information 26 for other area sections. FIG. 5 is a diagram showing an example of movement guidance information 26 stored in the cache 47.

As shown in FIG. 5 , in the cache 47, movement guidance information 26 is stored so as to be divided on a mesh-by-mesh basis which is a section-by-section basis of map information, and is set with remaining priorities. Note that in the present embodiment the remaining priority is set to either “A (high)” or “B (low)”. Therefore, in the example shown in FIG. 5 , since movement guidance information 26 for a mesh E and a mesh H has a lower remaining priority than movement guidance information 26 for a mesh A and a mesh B, the mesh E and the mesh H are deleted from the cache 47 on a priority basis. Note that although in the present embodiment the remaining priority is set to two levels, the remaining priority may be set to more detailed levels. Note also that the remaining priorities may be stored so as to be associated with meshes (area sections) instead of movement guidance information 26.

Meanwhile, the navigation ECU (electronic control unit) 33 is an electronic control unit that performs overall control of the communication terminal 5, and includes a CPU 51 serving as a computing device and a control device; and internal storage devices such as a RAM 52 that is used as a working memory when the CPU 51 performs various types of arithmetic processing and that stores route data obtained when a route is searched for, etc., a ROM 53 having recorded therein a movement guidance processing program which will be described later (see FIGS. 6 and 7 ), etc., in addition to a program for control, and a flash memory 54 that stores a program read from the ROM 53. Note that the navigation ECU 33 includes various types of means serving as processing algorithms with the ECU of the server device 3. For example, guidance information requesting means requests the server device 3 for guidance information for providing vehicle movement guidance after starting up the communication terminal 5, the guidance information being targeted for at least update target areas around a current location among update target areas which are areas whose terminal-side map information 48 included in the communication terminal 5 is an older version of map information than device-side map information 25 included in the server device 3. Guidance information receiving means receives movement guidance information 26 transmitted from the server device 3 in response to the request for movement guidance information 26. Guiding means provides vehicle travel guidance using a guidance route set on the communication terminal 5 and the movement guidance information 26 received by the guidance information receiving means.

The operating part 34 is operated when, for example, a point of departure which is a travel start point and a destination which is a travel end point are inputted, and includes a plurality of operating switches such as various types of keys and buttons (not shown). Then, based on switch signals outputted by, for example, depression of various switches, the navigation ECU 33 performs control to perform corresponding various types of operation. Note that the operating part 34 may include a touch panel provided on the front of the liquid crystal display 35. Note also that the operating part 34 may include a microphone and an audio recognition device.

In addition, on the liquid crystal display 35 there are displayed a map image including roads, traffic information, operation guidance, an operation menu, guidance on keys, a guidance route from a point of departure to a destination, guidance information along the guidance route, news, weather forecasts, time, e-mails, TV programs, etc. Note that a HUD or a HMD may be used instead of the liquid crystal display 35.

In addition, the speaker 36 outputs audio guidance that provides guidance on travel along a guidance route or guidance on traffic information, based on an instruction from the navigation ECU 33.

In addition, the DVD drive 37 is a drive that can read data recorded on a recording medium such as a DVD or a CD. Then, based on the read data, for example, music or video is played back or the terminal-side map DB 45 is updated. Note that a card slot for performing reading and writing on a memory card may be provided instead of the DVD drive 37.

In addition, the communication module 38 is a communication device for receiving various information such as map update information, route information, movement guidance information, and traffic information which are transmitted from, for example, the server device 3, a VICS (registered trademark) center, or a probe center. The communication module 38 corresponds, for example, to a mobile phone or a DCM.

Next, a movement guidance processing program executed by the server device 3 and the communication terminal 5 in the movement guidance system 1 having the above-described configuration will be described based on FIGS. 6 and 7 . FIGS. 6 and 7 are flowcharts of the movement guidance processing program according to the present embodiment. Here, the movement guidance processing program is a program that is executed after turning on a vehicle's accessory (ACC) power supply, i.e., after starting up the communication terminal 5, and that searches for a route from a point of departure to a destination and provides travel guidance along a guidance route. Note, however, that when the communication terminal 5 is other than a navigation device, the program is executed after turning on the power to a main body of the communication terminal 5 (after startup), instead of the ACC power supply. Note that the program shown in the flowcharts in the following FIGS. 6, 7, and 12 is stored in the RAM or ROM included in the server device 3 and the communication terminal 5, and executed by the CPU 21 or the CPU 51.

First, a movement guidance processing program executed by the CPU 51 of the communication terminal 5 will be described based on FIG. 6 . At step (hereinafter, abbreviated as S) 1, the CPU 51 transmits to the server device 3 a request for update information (hereinafter, referred to as table update information) for updating the update area table 49 included in the communication terminal 5 (hereinafter, referred to as a table update request). As described previously, the update area table 49 is a table in which flags that identify a section corresponding to an update target area and a section not corresponding to an update target area are assigned on a section-by-section basis (e.g., on a mesh-by-mesh basis) of map information (FIG. 4 ).

In addition, the table update request transmitted at the above-described S1 includes a terminal ID that identifies the communication terminal 5 which is the source of the request for table update information; and information that identifies the versions of pieces of terminal-side map information 48 at the present time on a section-by-section basis of map information. Note that for the information that identifies the versions of pieces of terminal-side map information 48, specifically, information is transmitted that identifies the creation times of pieces of map update information (update programs) having made the last update to the pieces of terminal-side map information 48 (the creation times also correspond to the times when pieces of current map information are created). Note that version numbers or the updated dates and times on which the last update is made may be transmitted. Note also that the information that identifies the versions of pieces of terminal-side map information 48 at the present time is stored in the version management DB 46.

Then, at S2, the CPU 51 receives table update information transmitted from the server device 3 in response to the table update request. Here, the table update information received at the above-described S2 is information that is created by the server device 3 by comparing the versions of pieces of terminal-side map information 48 at the present time with the versions of pieces of device-side map information 25 (S32), and that updates a section whose device-side map information 25 has been updated using map update information (update program) which is created after the creation time of map update information having made the last update to terminal-side map information 48 (i.e., a section whose device-side map information 25 has a newer creation time than terminal-side map information 48), to an update target area. Note that when the communication terminal 5 has transmitted version numbers together with a table update request to the server device 3, table update information can be created by comparing the version numbers, but a possible case in which a version number is downgraded to an old number (version downgrade) needs to be considered. FIG. 8 is a diagram showing an example of table update information.

For example, when, as shown in FIG. 8 , the versions of pieces of terminal-side map information 48 included in the communication terminal 5 are all “50”, and of the meshes forming device-side map information 25 included in the server device 3, a total of six meshes have the version “60” having been updated using map update information created at a time newer than the version “50”, table update information is created that updates corresponding six meshes to update target areas in the update area table 49. As described previously, in the update area table 49, the flag “0” is assigned to a mesh corresponding to an update target area and the flag “1” is assigned to a mesh not corresponding to an update target area (FIG. 4 ). Therefore, the table update information is data that overwrites the flags assigned to the corresponding six meshes with “0”.

Subsequently, at S3, the CPU 51 updates the update area table 49 based on the table update information received from the server device 3 at the above-described S2. Specifically, as shown in FIG. 9 , by combining the update area table 49 with the table update information, of the flags included in the update area table 49, flags assigned to meshes specified by the table update information (in the example shown in FIG. 9 , a total of six meshes) are overwritten with “0”. Note that of the meshes specified by the table update information, a mesh whose flag is already “0” maintains the “0” state.

As a result of updating the update area table 49 at the above-described S3, it becomes possible to accurately reflect areas (i.e., update target areas) whose terminal-side map information 48 included in the communication terminal 5 is an older version of map information than device-side map information 25 included in the server device 3 at the present time (after starting up the communication terminal 5 and before requesting the server device 3 for movement guidance information), in the update area table 49. Therefore, for example, when device-side map information 25 or terminal-side map information 48 is updated to a new version of map information, the update area table 49 is also updated accordingly. Note that the processes at the above-described S1 to S3 do not necessarily need to be performed every time the communication terminal 5 starts up, and for the timing at which the processes are performed, too, for example, the processes may be performed after setting a guidance route or may be performed during movement guidance.

Subsequently, at S4, the CPU 51 identifies a current vehicle location based on detection results obtained by the current location detecting part 31 and map information. Note that when a current vehicle location is identified, a map matching process for matching the current vehicle location to map information is performed. The current vehicle location is basically identified based on the terminal-side map information 48 included in the communication terminal 5, but when the version of terminal-side map information 48 for an area in which the vehicle is currently located is older than that of device-side map information 25 (i.e., when the area is an update target area), the current vehicle location is identified using movement guidance information 26 stored in the cache 47, instead of an old version of map information and movement guidance information stored in the terminal-side map DB 45. Note, however, that when the cache 47 does not have movement guidance information 26 for the corresponding area, the current vehicle location is identified using an old version of map information and movement guidance information stored in the terminal-side map DB 45.

Thereafter, at S5, the CPU 51 identifies “update target areas around the current vehicle location”, based on the update area table 49 and the current vehicle location identified at the above-described S4. Specifically, the CPU 51 first identifies a total of nine (3×3) meshes with a mesh in which the vehicle is currently located being at the center, as meshes around the current vehicle location. For example, in an example shown in FIG. 10 , since the mesh in which the vehicle is currently located is a “mesh Q”, the meshes around the current vehicle location are meshes K, L, M, P, Q, R, U, V, and W with the mesh Q being at the center. Thereafter, it is determined, by referring to the update area table 49, whether the meshes K, L, M, P, Q, R, U, V, and W correspond to update target areas, and meshes determined to correspond to update target areas, i.e., meshes assigned the flag “0” in the update area table 49, are identified as “update target areas around the current vehicle location”.

Subsequently, at S6, the CPU 51 transmits to the server device 3 a request for movement guidance information 26 targeted for the “update target areas around the current vehicle location” identified at the above-described S5, on the condition that the communication terminal 5 has started up. Note, however, that an area for which identical movement guidance information 26 is already stored in the cache 47 of the communication terminal 5 is excluded from request targets. Here, the movement guidance information 26 is, as described previously, information for identifying a current location, providing simple travel guidance along a guidance route, and displaying an image on the communication terminal 5 according to the latest version of map information included in the server device 3. Note that the request for movement guidance information transmitted at the above-described S6 includes a terminal ID that identifies the communication terminal 5 which is the source of the request for movement guidance information; and information (e.g., mesh identification numbers) that identifies target areas whose movement guidance information is requested (the “update target areas around the current vehicle location” identified at the above-described S6).

Thereafter, at S7, the CPU 51 receives movement guidance information 26 transmitted from the server device 3 in response to the request for movement guidance information 26. Note that the movement guidance information 26 includes matching data required to perform vehicle map-matching; guidance data required for guidance for allowing the vehicle to travel along a guidance route, such as left or right turn guidance at guidance intersections; and display data for displaying a map image and a guidance screen. Namely, the movement guidance information 26 received at the above-described S7 is information for identifying a current location, providing simple travel guidance along a guidance route, and displaying an image in the update target areas around the current vehicle location.

Note that the process at the above-described S7 is not always performed before processes at and after the following S8, and is performed at timing at which movement guidance information 26 is transmitted from the server device 3. Therefore, if the timing at which movement guidance information 26 is transmitted from the server device 3 is delayed, then the process at S7 may be performed during or after processes at S8 to S11. Note, however, that in order to prevent the occurrence of an event in which movement guidance based on a guidance route is not provided or erroneous guidance is provided, it is desirable that the reception of movement guidance information (S7) be performed before reception of searched-route information (S12). Note that the same also applies to S19 and S24 which will be described later.

Note that in the present embodiment since movement guidance information 26 is obtained from the server device 3 after starting up the communication terminal 5 and before performing a destination setting operation, even before setting a destination, vehicle travel guidance (e.g., display of neighboring map information) based on a new version of map information can be provided soon after startup.

In addition, at S8, the CPU 51 performs a cache management process which will be described later (FIG. 12 ). In the cache management process, as will be described later, the movement guidance information 26 obtained from the server device 3 is saved in the cache 47 of the communication terminal 5, and unnecessary information is deleted from the cache 47.

Then, at S9, the CPU 51 sets a destination of a route on the communication terminal 5. Note that the destination is basically set based on a user's operation accepted by the operating part 34 (e.g., an operation of reading a registered location or an operation of retrieving or selecting a facility). Note, however, that in the case of performing a re-search (rerouting), a destination currently set on the communication terminal 5 is continuously set without newly setting a destination.

Thereafter, at S10, the CPU 51 performs a route search process for a route from a point of departure to the destination set at the above-described S9, using the terminal-side map information 48 included in the communication terminal 5, and thereby identifies a recommended route from the point of departure to the destination (hereinafter, referred to as a terminal's recommended route). Specifically, a link cost which is a numerical representation of the level of appropriateness of a link (road) for a route, an intersection cost which is a numerical representation of the level of appropriateness of an intersection (node) for the route, a charge cost which is a numerical representation of the level of cost required for travel, etc., are calculated based on link data, node data, search data, etc., which are included in the terminal-side map information 48, and a terminal's recommended route is searched for using the calculated search costs. For example, using the publicly known Dijkstra's algorithm, a route with the smallest total of cost values is determined to be a terminal's recommended route. Note that a route search process using the Dijkstra's algorithm is already publicly known and thus a detail thereof is omitted. Note also that the point of departure may be a current vehicle location or may be an arbitrary location (e.g., user's home) specified by the user.

Subsequently, at S11, the CPU 51 transmits a route search request for requesting to search for a route from the point of departure to the destination, to the server device 3. Here, the route search request includes a terminal ID that identifies the communication terminal 5 which is the source of the route search request; information that identifies the point of departure (e.g., a current vehicle location) and the destination set at the above-described S4 which are search conditions for a route search; and route information that identifies the terminal's recommended route which is searched for at the above-described S10. Note, however, that upon performing rerouting due to the vehicle deviating from a guidance route, since the destination is basically the same as that for the last search, information that identifies the destination does not need to be transmitted.

In addition, for the route information that identifies the terminal's recommended route, information that identifies the entire terminal's recommended route may be transmitted, but only information that identifies particularly a road sequence of the terminal's recommended route that continues ahead from the point of departure within a predetermined distance from the point of departure may be transmitted.

Thereafter, at S12, the CPU 51 receives searched-route information transmitted from the server device 3 in response to the route search request. Here, the searched-route information received at the above-described S12 is information about a recommended route from the point of departure to the destination (hereinafter, referred to as a server's recommended route) that is searched for by the server device 3 using the device-side map information 25 which is the latest version of map information, based on the route search request transmitted at the above-described S11.

Subsequently, at S13, the CPU 51 determines whether to set the server's recommended route received at the above-described S12 as a guidance route for the communication terminal 5. Note that when a server's recommended route is received from the server device 3, the received server's recommended route is basically set as a guidance route for the communication terminal 5. Note, however, that when a server's recommended route has not been able to be received from the server device 3 due to, for example, a communication error, a route other than a server's recommended route, such as the terminal's recommended route searched for by the communication terminal 5 at the above-described S10, is set as a guidance route for the communication terminal 5.

Then, if it is determined to set a route other than a server's recommended route as a guidance route for the communication terminal 5 (S13: NO), processing transitions to S14.

At S14, the CPU 51 sets, for example, the terminal's recommended route searched for in the route search process at the above-described S10, as a target guidance route for which vehicle travel guidance is provided on the communication terminal 5. Thereafter, vehicle travel guidance starts based on the set guidance route. For example, a map image including a road network around the vehicle location is displayed, or when a target guidance divergence point at which a left or right turn is made approaches a predetermined distance ahead of the vehicle, an enlarged view of the guidance divergence point is displayed or guidance on a vehicle traveling direction at the guidance divergence point is provided. In addition, at the above-described S14, the CPU 51 basically provides the above-described travel guidance, based on the terminal-side map information 48 and the movement guidance information 26 which are stored in the terminal-side map DB 45. Here, since the terminal's recommended route searched for in the route search process at the above-described S10 is a route searched for based on the terminal-side map information 48 included in the communication terminal 5, even if an old version of movement guidance information 26 is used instead of a new version of movement guidance information 26 obtained from the server device 3, a current vehicle location can be identified at a correct location and guidance can be provided, and at a guidance intersection, guidance on a correct vehicle traveling direction can be provided. Note, however, that for areas having a new version of movement guidance information 26 obtained from the server device 3, the above-described travel guidance may be provided using the movement guidance information 26.

On the other hand, if it is determined to set the server's recommended route received at the above-described S12, as a guidance route for the communication terminal 5 (S13: YES), processing transitions to S15.

At S15, the CPU 51 sets the server's recommended route received at the above-described S12, as a target guidance route for which vehicle travel guidance is provided on the communication terminal 5. Thereafter, vehicle travel guidance starts based on the set guidance route. For example, a map image including a road network around the vehicle location is displayed, or when a target guidance divergence point at which a left or right turn is made approaches a predetermined distance ahead of the vehicle, an enlarged view of the guidance divergence point is displayed or guidance on a vehicle traveling direction at the guidance divergence point is provided. In addition, at the above-described S15, the CPU 51 basically provides the above-described travel guidance, based on the terminal-side map information 48 and the movement guidance information 26 which are stored in the terminal-side map DB 45. Note, however, that when the terminal-side map information 48 or movement guidance information 26 stored in the terminal-side map DB 45 is not the latest version for areas around the current vehicle location or areas around the guidance route, the above-described travel guidance is provided using also movement guidance information 26 that is obtained from the server device 3 and stored in the cache 47. Note that since the movement guidance information 26 includes matching data required to perform vehicle map-matching; guidance data required for guidance for allowing the vehicle to travel along a guidance route, such as left or right turn guidance at guidance intersections; and display data for displaying a map image and a guidance screen, even if the terminal-side map information 48 or movement guidance information 26 stored in the terminal-side map DB 45 is not the latest version, it becomes possible to appropriately provide travel guidance along a guidance route that is searched for based on the latest version of map information.

Subsequently, at S16, the CPU 51 obtains the guidance route set on the communication terminal 5 at the present time.

Then, at S17, the CPU 51 identifies “update target areas around the guidance route”, based on the update area table 49 and the guidance route obtained at the above-described S16. Specifically, the CPU 51 first identifies meshes including at least a part of the guidance route within a predetermined distance L from the current vehicle location in the direction of the destination, as meshes around the guidance route. For example, in an example shown in FIG. 11 , the meshes including at least a part of a guidance route 61 within a predetermined distance L from a current vehicle location in the direction of a destination are meshes H, M, Q, and R. Thereafter, it is determined, by referring to the update area table 49, whether the meshes H, M, R, and Q correspond to update target areas, and meshes determined to correspond to update target areas, i.e., meshes assigned the flag “0” in the update area table 49, are identified as “update target areas around the guidance route”.

Subsequently, at S18, the CPU 51 transmits a request for movement guidance information 26 targeted for the “update target areas around the guidance route” identified at the above-described S5, to the server device 3. Note, however, that an area for which identical movement guidance information 26 is already stored in the cache 47 of the communication terminal 5 is excluded from request targets. Note that the request for movement guidance information transmitted at the above-described S18 includes a terminal ID that identifies the communication terminal 5 which is the source of the request for movement guidance information; and information (e.g., mesh identification numbers) that identifies target areas whose movement guidance information is requested (the “update target areas around the guidance route” identified at the above-described S17).

Thereafter, at S19, the CPU 51 receives movement guidance information 26 transmitted from the server device 3 in response to the request for movement guidance information 26. Note that the movement guidance information 26 includes matching data required to perform vehicle map-matching; guidance data required for guidance for allowing the vehicle to travel along a guidance route, such as left or right turn guidance at guidance intersections; and display data for displaying a map image and a guidance screen. Namely, the movement guidance information 26 received at the above-described S19 is information for identifying a current location, providing simple travel guidance along a guidance route, and displaying an image in the update target areas around the guidance route.

In addition, at S20, the CPU 51 performs a cache management process which will be described later (FIG. 12 ). In the cache management process, as will be described later, the movement guidance information 26 obtained from the server device 3 is saved in the cache 47 of the communication terminal 5, and unnecessary information is deleted from the cache 47.

Subsequently, at S21, the CPU 51 determines whether the vehicle has crossed a section (e.g., a mesh) of map information.

Then, if it is determined that the vehicle has crossed a section of map information (S21: YES), processing transitions to S22. On the other hand, if it is determined that the vehicle has not crossed a section of map information (S21: NO), processing transitions to S26.

At S22, the CPU 51 identifies “update target areas around the current vehicle location” and “update target areas around the guidance route”, based on the update area table 49, the current vehicle location, and the guidance route obtained at the above-described S16. Note that the identification of the “update target areas around the current vehicle location” is the same process as that at S5 and the “update target areas around the guidance route” are the same process as that at S17, and thus, a detail thereof is omitted.

Subsequently, at S23, the CPU 51 transmits to the server device 3 a request for movement guidance information 26 targeted for the “update target areas around the current vehicle location” and the “update target areas around the guidance route” which are identified at the above-described S22. Note, however, that an area for which identical movement guidance information 26 is already stored in the cache 47 of the communication terminal 5 is excluded from request targets. Note that the request for movement guidance information transmitted at the above-described S23 includes a terminal ID that identifies the communication terminal 5 which is the source of the request for movement guidance information; and information (e.g., mesh identification numbers) that identifies target areas whose movement guidance information is requested (the “update target areas around the current vehicle location” and the “update target areas around the guidance route” which are identified at the above-described S21).

Thereafter, at S24, the CPU 51 receives movement guidance information 26 transmitted from the server device 3 in response to the request for movement guidance information 26. Note that the movement guidance information 26 includes matching data required to perform vehicle map-matching; guidance data required for guidance for allowing the vehicle to travel along a guidance route, such as left or right turn guidance at guidance intersections; and display data for displaying a map image and a guidance screen. Namely, the movement guidance information 26 received at the above-described S24 is information for identifying a current location, providing simple travel guidance along a guidance route, and displaying an image in the update target areas around the current vehicle location and the update target areas around the guidance route.

In addition, at S25, the CPU 51 performs a cache management process which will be described later (FIG. 12 ). In the cache management process, as will be described later, the movement guidance information 26 obtained from the server device 3 is saved in the cache 47 of the communication terminal 5, and unnecessary information is deleted from the cache 47. Thereafter, processing transitions to S26.

At S26, the CPU 51 determines whether the vehicle has reached the destination.

Then, if it is determined that the vehicle has reached the destination (S26: YES), the movement guidance processing program ends. On the other hand, if it is determined that the vehicle has not reached the destination (S26: NO), processing returns to S21 and the reception of movement guidance information and travel guidance using the received movement guidance information are continuously performed.

Next, a movement guidance processing program executed by the CPU 21 of the server device 3 will be described. Note that processes at the following S31 to S33, S34 to S36, S37 to S39, S40 to S42, and S43 to S45 each start at timing at which corresponding information from the communication terminal 5 is received, and are performed in parallel to each other. Therefore, the steps are not always performed in ascending order of their step numbers. For example, when a route search request is received from the communication terminal 5 before completing a process at S35 which will be described later, S37 and S38 are performed before S36.

First, at S31, the CPU 21 receives a table update request transmitted from the communication terminal 5 having started up. Note that the table update request includes a terminal ID that identifies the communication terminal 5 which is the source of the table update request; and information that identifies the versions of pieces of terminal-side map information 48 at the present time on a section-by-section basis of map information. When a table update request is received from the communication terminal 5, processes at the following S32 and S33 are performed.

At S32, the CPU 21 creates table update information for updating the update area table 49 included in the communication terminal 5, based on the table update request received at the above-described S31. Specifically, the versions of pieces of terminal-side map information 48 at the present time which are received at the above-described S31 are compared with the versions of pieces of device-side map information 25 included in the server device 3, to identify a section (e.g., a mesh) whose device-side map information 25 has been updated using map update information (update program) which is created after the creation time of map update information having made the last update to terminal-side map information 48. Then, table update information is created that updates flags for the identified sections to “0 (update target area)” among the flags included in the update area table 49 (FIG. 8 ).

Thereafter, at S33, the CPU 21 transmits the table update information created at the above-described S32 to the requested communication terminal 5. Then, the communication terminal 5 having received the table update information updates the update area table 49 based on the received table update information (S3).

In addition, at S34, the CPU 21 receives a request for movement guidance information 26 which is transmitted from the communication terminal 5 having updated the update area table 49. Note that the request for movement guidance information 26 includes a terminal ID that identifies the communication terminal 5 which is the source of the request for movement guidance information; and information (e.g., mesh numbers) that identifies target areas whose movement guidance information is requested (the update target areas around the current vehicle location which are identified at the above-described S6). When a request for movement guidance information 26 is received from the communication terminal 5, processes at the following S35 and S36 are performed.

At S35, the CPU 21 extracts movement guidance information 26 for the corresponding areas from the device-side map DB 12, based on the request for movement guidance information 26 received at the above-described S34.

Thereafter, at S36, the CPU 21 transmits the movement guidance information 26 extracted at the above-described S35 to the requested communication terminal 5.

In addition, at S37, the CPU 21 receives a route search request transmitted from the communication terminal 5. Note that the route search request includes a terminal ID that identifies the communication terminal 5 which is the source of the route search request; information that identifies a point of departure (e.g., a current vehicle location) and the destination set at the above-described S9 which are search conditions for a route search; and route information that identifies the terminal's recommended route which is searched for at the above-described S10. When a route search request is received from the communication terminal 5, processes at the following S38 and S39 are performed.

Then, at S38, the CPU 21 performs a route search process for a route from the point of departure to the destination, using the route search request received at the above-described S37 and the device-side map information 25 included in the server device 3, and thereby identifies a recommended route from the point of departure to the destination (server's recommended route). Note that the server's recommended route is a route including at least a part of the terminal's recommended route which is searched for by the communication terminal 5. More specifically, a route to the destination that is connected to a portion of the terminal's recommended route within a predetermined distance from the point of departure is searched for, and a route obtained by combining the portion of the terminal's recommended route within the predetermined distance from the point of departure with the searched route is determined to be a server's recommended route.

Subsequently, at S39, the CPU 21 transmits searched-route information that identifies the server's recommended route identified at the above-described S38, to the communication terminal 5 which is the source of the route search request. As a result, the server's recommended route is set as a guidance route on the communication terminal 5. Note that in order to prevent the occurrence of an event in which movement guidance based on a guidance route is not provided or erroneous guidance is provided, it is desirable that the transmission of movement guidance information (S36) be performed before the transmission of searched-route information (S39).

In addition, at S40, the CPU 21 receives a request for movement guidance information 26 which is transmitted from the communication terminal 5 having set a guidance route. Note that the request for movement guidance information 26 includes a terminal ID that identifies the communication terminal 5 which is the source of the request for movement guidance information; and information (e.g., mesh numbers) that identifies target areas whose movement guidance information is requested (the update target areas around the guidance route which are identified at the above-described S17). When a request for movement guidance information 26 is received from the communication terminal 5 having set a guidance route, processes at the following S41 and S42 are performed.

Subsequently, at S41, the CPU 21 extracts movement guidance information 26 for the corresponding areas from the device-side map DB 12, based on the request for movement guidance information 26 received at the above-described S40.

Thereafter, at S42, the CPU 21 transmits the movement guidance information 26 extracted at the above-described S41 to the requested communication terminal 5.

In addition, at S43, the CPU 21 receives a request for movement guidance information 26 which is transmitted from the communication terminal 5 having crossed a section of map information. Note that the request for movement guidance information 26 includes a terminal ID that identifies the communication terminal 5 which is the source of the request for movement guidance information; and information (e.g., mesh numbers) that identifies target areas whose movement guidance information is requested (the update target areas around the current vehicle location and around the guidance route which are identified at the above-described S22). When a request for movement guidance information 26 is received from the communication terminal 5 having crossed a section of map information, processes at the following S44 and S45 are performed.

Subsequently, at S44, the CPU 21 extracts movement guidance information 26 for the corresponding areas from the device-side map DB 12, based on the request for movement guidance information 26 received at the above-described S43.

Thereafter, at S45, the CPU 21 transmits the movement guidance information 26 extracted at the above-described S44 to the requested communication terminal 5.

Next, a sub-process of the cache management process performed at the above-described S8, S20, and S25 will be described based on FIG. 12 . FIG. 12 is a flowchart of a sub-processing program for the cache management process.

First, at S51, the CPU 51 determines whether the free space in the cache 47 is less than or equal to a threshold value. Note that the threshold value is the maximum size of movement guidance information 26 that is possibly obtained at a time from the server device 3.

Then, if it is determined that the free space in the cache 47 is less than or equal to the threshold value (S51: YES), processing transitions to S54. On the other hand, if it is determined that the free space in the cache 47 is larger than the threshold value (S51: NO), processing transitions to S52.

At S52, the CPU 51 stores movement guidance information 26 received from the server device 3 in the cache 47. Note that the movement guidance information 26 stored in the cache 47 is used later to identify a current location, provide simple travel guidance along a guidance route, and display an image on the communication terminal 5.

Then, at S53, the CPU 51 sets remaining priorities for the movement guidance information 26 that is newly stored in the cache 47 at the above-described S52, on a per area section basis. Note that the remaining priorities are information for sorting movement guidance information 26 to be deleted when the storage area of the cache 47 is lacking. Specifically, of the pieces of movement guidance information 26 stored in the cache 47, pieces of movement guidance information 26 with a low remaining priority are deleted on a priority basis.

Specifically, at the above-described S53, the CPU 51 identifies area sections that require movement guidance information 26 for the future vehicle movement guidance, more specifically, “area sections located around the current vehicle location” and “area sections located around the guidance route set on the communication terminal 5”. Then, movement guidance information 26 for the identified area sections is set with a higher remaining priority than movement guidance information 26 for other area sections. Here, the movement guidance information 26 that is newly stored in the cache 47 at the above-described S52 is movement guidance information 26 for area sections located around the current vehicle location or area sections located around the guidance route set on the communication terminal 5. Therefore, at the above-described S53, the remaining priorities are basically set to “A (high)”. Note that movement guidance information 26 for area sections other than the area sections located around the current vehicle location or the area sections located around the guidance route may also be likewise set with a high remaining priority as long as the area sections are determined to require movement guidance information 26 for the future vehicle movement guidance.

On the other hand, at S54, the CPU 51 updates remaining priorities set for respective pieces of movement guidance information 26 stored in the cache 47, on a per area section basis. Here, as shown in FIG. 5 , the movement guidance information 26 stored in the cache 47 is set with remaining priorities on a section-by-section basis (e.g., on a mesh-by-mesh basis) of map information. At the above-described S54, the CPU 51 updates the remaining priorities according to the following conditions (1) and (2):

-   -   (1) Movement guidance information 26 for area sections located         around the current vehicle location (e.g., 3×3 meshes with the         current vehicle location being at the center) or area sections         located around the guidance route set on the communication         terminal 5 (e.g., meshes including the guidance route) is highly         likely to be required for the future vehicle movement guidance         and thus is set with the remaining priority “A (high)”. On the         other hand, movement guidance information 26 for other area         sections is less likely to be required in the future and thus is         set with the remaining priority “B (low)”.     -   (2) Note, however, that regardless of the above-described (1),         movement guidance information 26 for area sections whose         terminal-side map information 48 is the latest version, i.e.,         area sections for which the communication terminal 5 can provide         travel guidance based on the latest version of map information         without using movement guidance information 26, is set with the         remaining priority “B (low)”.

Thereafter, at S55, the CPU 51 deletes pieces of movement guidance information 26 with a low remaining priority on a priority basis among the pieces of movement guidance information 26 stored in the cache 47. Specifically, pieces of movement guidance information 26 set with the remaining priority “B (low)” are deleted from the cache on a per area section (mesh) basis.

Thereafter, at S56, the CPU 51 determines again whether the free space in the cache 47 is less than or equal to the threshold value.

Then, if it is determined that the free space in the cache 47 is less than or equal to the threshold value (S56: YES), processing transitions to S57. On the other hand, if the free space in the cache 47 is larger than the threshold value (S56: NO), processing transitions to S52.

At S57, the CPU 51 temporarily increases storage space allocated to the cache 47 in the hard disk or memory. Note that the space to be increased is such an amount of space at which the increased free space in the cache 47 is larger than the threshold value which is a criterion of determination at the above-described S51. In addition, the configuration may be such that the increased space in the cache is put back later at timing at which the free area in the cache 47 has increased, or the configuration may be such that the increased space is not put back. Thereafter, processing transitions to S52.

As described in detail above, in the movement guidance system 1, the server device 3, the communication terminal 5, and the computer program executed by the server device 3 and the communication terminal 5 according to the present embodiment, after starting up the communication terminal 5, update target areas are identified which are areas whose terminal-side map information 48 included in the communication terminal 5 is an older version of map information than device-side map information 25 included in the server device 3 (S5); a request for movement guidance information 26 targeted for at least update target areas around a current location is made to the server device 3, the movement guidance information 26 being used to provide movement guidance for a mobile unit (S6); and movement guidance for the mobile unit is provided using movement guidance information 26 transmitted from the server device 3 in response to the request (S15). Thus, it becomes possible to provide movement guidance based on a new version of map information soon after starting up the communication terminal 5. In addition, upon performing a center route search, by obtaining in advance movement guidance information 26 for providing movement guidance for the mobile unit, the occurrence of an event in which after the communication terminal 5 obtains a guidance route from the server device 3, movement guidance based on the guidance route is not provided or erroneous guidance is provided can be prevented as much as possible. As a result, even if map information included in the communication terminal 5 is an older version of map information compared to map information included in the server device 3, it becomes possible to appropriately provide movement guidance for the mobile unit based on a guidance route searched for by the server device 3. Furthermore, instead of map information (including facility data, data used for a route search, etc., in addition to guidance information for providing movement guidance), the guidance information which is part of the map information is selectively obtained in advance from the server device, and thus, it becomes possible to reduce the amount of information delivered compared to the case of obtaining map information.

Note that the above-described embodiment need not be limiting and it is, of course, possible to make various modifications and alterations thereto without departing from the spirit and scope of the broad inventive principles.

For example, although in the present embodiment the configuration is such that the communication terminal 5 performs processes for identifying update target areas around a current vehicle location and around a guidance route at the above-described S5, S17, and S22, the configuration may be such that the server device 3 performs the processes. In that case, the server device 3 needs to have or obtain from the communication terminal 5 the update area table 49, a current vehicle location, and a guidance route set on the communication terminal 5.

In addition, although in the present embodiment the configuration is such that the communication terminal 5 requests the server device 3 for movement guidance information 26 targeted for update target areas around a current vehicle location and update target areas around a guidance route, the communication terminal 5 may also request the server device 3 for movement guidance information 26 targeted for update target areas in an area where a map image is displayed on the liquid crystal display 35. As a result, for example, when a map image displayed on the liquid crystal display 35 is scroll-displayed, it becomes possible to display a map image based on the latest version of map information.

In addition, although in the present embodiment the configuration is such that remaining priorities set for movement guidance information 26 are updated immediately before deleting movement guidance information from the cache 47 (S54), the remaining priorities may be updated at timing, e.g., at predetermined time intervals, upon startup of the communication terminal 5, or at a time point when the vehicle has crossed a mesh.

In addition, although in the present embodiment, when the communication terminal 5 requests the server device 3 for movement guidance information 26, identical movement guidance information 26 that is already stored in the cache 47 of the communication terminal 5 is excluded from request targets, the identical movement guidance information 26 may be included in request targets.

In addition, although in the present embodiment, when the communication terminal 5 requests the server device 3 for movement guidance information for update target areas around a guidance route, meshes including at least a part of the guidance route within a predetermined distance L from a current vehicle location in the direction of a destination serve as targets, regardless of the distance from the current vehicle location, meshes including at least a part of the guidance route may serve as targets.

In addition, although in the present embodiment the update area table 49 is a table in which a mesh corresponding to an update target area and a mesh not corresponding to an update target area are identified on a per mesh basis of map information (FIG. 4 ), the identification may be performed, for example, on a per administrative district basis such as a city, a ward, a town, or a village, instead of on a per mesh basis.

In addition, although in the present embodiment the movement guidance information 26 is information divided on a per mesh basis of map information (FIG. 5 ), the movement guidance information 26 may be information divided, for example, on a per administrative district basis such as a city, a ward, a town, or a village, instead of on a per mesh basis. In addition, when remaining priorities are set for the movement guidance information 26, too, the remaining priorities may be likewise set on a per administrative district basis instead of on a per mesh basis.

In addition, although in the present embodiment the communication terminal 5 requests the server device 3 for movement guidance information 26 for areas around a current location (S6) after updating the update area table (S3), the request for movement guidance information may be made immediately after startup of the communication terminal 5 which is before updating the update area table.

In addition, although an implementation example is described above in which a communication terminal, a server device, a movement guidance system, and a computer program are embodied, the communication terminal can also have the following configurations and in that case the following advantageous effects are provided.

For example, a first configuration is as follows:

-   -   A communication terminal (5) that is connected to a server         device (3) in a two-way communicable manner and that transmits a         route search request for a destination to the server device and         obtains a route searched for and delivered by the server device         in response to the route search request includes: guidance         information requesting means for requesting the server device         for guidance information after starting up the communication         terminal, the guidance information being used to provide         movement guidance for a mobile unit and being targeted for at         least the update target area around a current location among         update target areas, the update target areas being areas whose         terminal-side map information (48) included in the communication         terminal is an older version of map information than device-side         map information (25) included in the server device; guidance         information receiving means (33) for receiving the guidance         information transmitted from the server device in response to         the request for the guidance information; and guiding means (33)         for providing movement guidance for the mobile unit using a         guidance route set on the communication terminal and the         guidance information received by the guidance information         receiving means.     -   According to the communication terminal having the         above-described configuration, since guidance information for         providing movement guidance for the mobile unit is obtained         after starting up the communication terminal, it becomes         possible to provide movement guidance based on a new version of         map information soon after starting up the communication         terminal. In addition, upon performing a center route search, by         obtaining in advance guidance information for providing movement         guidance for the mobile unit, the occurrence of an event in         which after the communication terminal obtains a guidance route         from the server device, movement guidance based on the guidance         route is not provided or erroneous guidance is provided can be         prevented as much as possible. As a result, even if map         information included in the communication terminal is an older         version of map information compared to map information included         in the server device, it becomes possible to appropriately         provide movement guidance for the mobile unit based on a         guidance route searched for by the server device. Furthermore,         instead of map information (including facility data, data used         for a route search, etc., in addition to guidance information         for providing movement guidance), the guidance information which         is part of the map information is selectively obtained in         advance from the server device, and thus, it becomes possible to         reduce the amount of information delivered compared to the case         of obtaining map information.

In addition, a second configuration is as follows:

-   -   The guidance information requesting means makes a request for         the guidance information after starting up the communication         terminal and before setting a destination.

According to the communication terminal having the above-described configuration, since guidance information for providing movement guidance for the mobile unit is obtained before the communication terminal obtains a guidance route from the server device, it becomes possible to appropriately provide movement guidance for the mobile unit based on the guidance route searched for by the server device.

In addition, a third configuration is as follows:

-   -   The update target areas are identified based on area         identification information (49) in which sections corresponding         to the update target areas and sections not corresponding to the         update target areas are identified on a section-by-section basis         of map information.     -   According to the communication terminal having the         above-described configuration, it becomes possible to easily and         promptly identify a section corresponding to an update target         area and a section not corresponding to an update target area,         without the need of a complex control process or communication         process.

In addition, a fourth configuration is as follows:

-   -   The update target areas are identified on a mesh-by-mesh basis.     -   According to the communication terminal having the         above-described configuration, by identifying update target         areas on a mesh-by-mesh basis, the mesh being the same as a         management section of map information, it becomes possible to         more easily perform processes for identifying update target         areas and making a request for guidance information which is         associated with the identification of update target areas. 

The invention claimed is:
 1. A communication terminal that is connected to a server device in a two-way communicable manner, the communication terminal comprising: a processor programmed to: request the server device for movement guidance information after starting up the communication terminal, the movement guidance information being used to provide movement guidance for a mobile unit and being targeted for at least an update target area around a current location among update target areas, the update target areas being areas whose terminal-side map information included in the communication terminal is an older version of map information than device-side map information included in the server device, the movement guidance information including information used to provide travel guidance, and display an image on the communication terminal; receive the movement guidance information transmitted from the server device in response to the request for the movement guidance information; provide movement guidance for the mobile unit using the received movement guidance information; after receiving the movement guidance information, transmit a route search request for a destination to the server device, wherein the movement guidance information is received before setting the destination and before providing the movement guidance; and after providing the movement guidance of the mobile unit, receive a route searched for and delivered by the server device in response to the transmitted request.
 2. The communication terminal according to claim 1, wherein the processor is programmed to make a request for the movement guidance information after starting up the communication terminal and before setting the destination.
 3. The communication terminal according to claim 1, wherein the update target areas are identified based on area identification information in which sections corresponding to the update target areas and sections not corresponding to the update target areas are identified on a section-by-section basis of map information.
 4. The communication terminal according to claim 1, wherein the update target areas are identified on a mesh-by-mesh basis.
 5. A computer-readable storage medium storing a computer-executable program storing instructions causing a communication terminal that is connected to a server device in a two-way communicable manner to perform functions comprising: requesting the server device for movement guidance information after starting up the communication terminal, the movement guidance information being used to provide movement guidance for a mobile unit and being targeted for at least an update target area around a current location among update target areas, the update target areas being areas whose terminal-side map information included in the communication terminal is an older version of map information than device-side map information included in the server device, the movement guidance information including information used to provide travel guidance, and display an image on the communication terminal; receiving the movement guidance information transmitted from the server device in response to the request for the movement guidance information; providing movement guidance for the mobile unit using the received movement guidance information; after receiving the movement guidance information, transmitting a route search request for a destination to the server device, wherein the movement guidance information is received before setting the destination and before providing the movement guidance; and after providing the movement guidance of the mobile unit, receiving a route searched for and delivered by the server device in response to the transmitted request.
 6. A server device that is connected to a communication terminal in a two-way communicable manner, the server device comprising: a processor programmed to: receive a request for movement guidance information for providing movement guidance for a mobile unit from the communication terminal having started up; transmit the movement guidance information to the communication terminal in response to the request for the movement guidance information, the movement guidance information being targeted for at least an update target area around a current location among update target areas, the update target areas being areas whose terminal-side map information included in the communication terminal is an older version of map information than device-side map information included in the server device, the movement guidance information including information used to provide travel guidance, and display an image on the communication terminal; after transmitting the movement guidance information, receive a route search request for a destination from the communication terminal, wherein the movement guidance information is transmitted before setting the destination; search for a route to the destination based on the received route search request; and transmit the searched for route to the communication terminal.
 7. A movement guidance system comprising a server device and a communication terminal that is connected to the server device in a two-way communicable manner and that transmits a route search request for a destination to the server device and obtains a route searched for and delivered by the server device in response the route search request, wherein: the communication terminal includes a first processor programmed to: request the server device for movement guidance information after starting up the communication terminal, the movement guidance information being used to provide movement guidance for a mobile unit and being targeted for at least an update target area around a current location among update target areas, the update target areas being areas whose terminal-side map information included in the communication terminal is an older version of map information than device-side map information included in the server device, the movement guidance information including information used to provide travel guidance, and display an image on the communication terminal; receive the movement guidance information transmitted from the server device in response to the request for the movement guidance information; provide movement guidance for the mobile unit using the received movement guidance information; after receiving the movement guidance information, transmit a route search request for a destination to the server device, wherein the movement guidance information is received before setting the destination and before providing the movement guidance; and after providing the movement guidance of the mobile unit, receive a route searched for and delivered by the server device in response to the transmitted request; and the server device includes a second processor programmed to: receive the request for the movement guidance information from the communication terminal; transmit the movement guidance information for a target area to the communication terminal in response to the request for the movement guidance information; receive the route search request for the destination from the communication terminal, wherein the movement guidance information is transmitted before setting the destination; search for the route to the destination based on the received route search request; and transmit the searched for route to the communication terminal. 